Chilling Omen of Global Warming?

A startling, and disquieting discovery recently emerged from the two decades of painstaking measurements of tree growth at La Selva by David and Deborah Clark. These measurements, precise to less than a millimeter, recently revealed that during warmer years, the trees grew less, died more, and expelled more carbon dioxide. At first blush this seems only an interesting scientific tidbit. However, its implications are deeply unsettling, says Deborah Clark.

“A major, tacit assumption, I think, of 90 percent of us working at La Selva was that we were working in a tropical rain forest, which means equitable climate, which means every year’s the same,” says Clark. However, the new finding, she says, “made it very clear to us that, if our forest is very sensitive to small, inter-year differences in climate, it’s certainly going to be affected with these global changes going on right now.”

The world’s climate could be entering what she calls “very scary territory,” in which the rise in global temperature, along with accompanying drought, could inflict enormous damage to tropical forests and increase the amount of carbon dioxide in the planet’s atmosphere.

Many ecologists had assumed that tropical forests would grow faster with higher levels of carbon dioxide, buffering the global increase in the greenhouse gas. In contrast, the scenario the Clarks' research hints at -- in which the death of tropical forests increases carbon dioxide rise and global warming -- has been ominously named the Armageddon Model.